A refracting telescope is an optical instrument that uses lenses to gather and focus light. The primary lens, called the objective lens, collects light from distant objects and brings it to a focus, creating an image. This image is then magnified by a smaller lens called the eyepiece, allowing the viewer to see details of celestial bodies like stars and planets. Refracting telescopes were historically significant in astronomy, with early models developed by Galileo Galilei in the early 17th century. They are still used today, particularly for observing the moon and planets, although they can be limited by factors like chromatic aberration, which causes color distortion in images.